Abstract: This experiment was conducted to investigate the effects of solid (SSF) and liquid-state fermentation (LSF) on the morphology and the production and enzymatic properties of tannase of recombinant Pichia pastoris. It was found that there were large differences between SSF and LSF in terms of the bacterial morphology and the production and enzymatic properties of tannase. The recombinant strain had a higher biomass accumulation in SSF, which was 22.3% higher than that in SMF after 48 h incubation. From scanning electron microscopic (SEM) analysis, it was found that individual cells of the recombinant strain were more prone to aggregation, accompanied by the emergence of biofilm in SSF. For both SSF and LSF, the enzyme production increased first and then decreased with methanol concentration, reaching its maximum at methanol concentrations of 2% and 3%, respectively. Furthermore, tanninases produced in SSF and LSF had different enzymatic properties, and their optimum temperatures were 30 and 20 ℃, respectively. The thermal stability of the former was slightly weaker than that of the latter, whereas no significant difference was found in any other enzymatic property tested. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that tanninase produced in SSF was modified, which may account for the above differences. In conclusion, the findings of this can provide a theoretical foundation for the efficient preparation of tannase.

Key words: tannase; solid-state fermentation; Pichia pastoris; submerged fermentation; enzymatic properties